Calculating unearned revenue?

On December 31, 2010, the balance in Pinnacle Exploration Corporation's Unearned Revenue is $4,200. In January, 2011 the company received an advance payment of $12,000 for services to be performed. By May 31, adjustments had been made to recognize $8,500 of the revenue. What would be the balance in Unearned Revenue on May 31, 2011?